Safety plug for tool and drill strings



Dec. 27, 1960 H.R.BEAN

SAFETY PLUG FOR TOOL AND DRILL STRINGS Filed March 25, 1959 2 Sheets-Sheet 1 0 fig "3 Hobart R. Bean INVENTOR 9 BY Wm mdWmwyEMg Dec. 27, 1960 H. R. BEAN 2,966,277

SAFETY PLUG FOR TOOL AND DRILL STRINGS Filed March 25, 1959 2 Sheets-Sheet 2 v 64 56 F lg. 3 92 84 44 3 42 35: l6 /a- 4 89 ,r: 7 .152 F v 76 55 78 76 Hobart R. Bean 1N VEN TOR.

WW 3 M United States Patent SAFETY PLUG FOR TOOL AND DRILL STRINGS Hobart R. Bean, P.O. Box 210, Magnolia, Ark.

Filed Mar. 25, 1959, Ser. No. 801,892

9 Claims. (Cl. 22025) This invention comprises a novel and useful safety plug for tool and drill strings and more particularly relates to a plug providing a removable closure for the upper end of a section or stand of a tool or drill string to prevent the escape of fluid therein as the associated section of the string is uncoupled from the immediately succeeding section thereof, whereby to obviate the dangerous and messy condition'of oil or fluids flowing across the floor of the drilling rig as the tool or drill string is withdrawn from the well bore.

In the normal course of drilling and in the production of oil and gas wells it is frequently necessary to pull or remove the drill pipe or tubing for various purposes such as to service the tool, to increase or shorten the length of the string, to make various tests upon the productivity or other conditions of the formation.

When the drill pipe or tubing is lifted and pulled from the well, it is of course usually or frequently filled with oil, gas or other fluids. Consequently, as the successive uppermost joints, sections or stands of the pipe are uncoupled from the lower sections, the fluid contained within the upper section will flow out from the uncoupled joint thus producing a dangerous as well as an undesirably messy condition upon the fioor of the drilling rig.

It is the primary purpose of this invention to provide a safety plug which may be easily and quickly secured to the upper end of the uppermost section of a drilling string or tubing so that when this uppermost section is removed, the closure afforded by this plug will prevent the draining of the fluids from this upper section until the latter has been removed to a convenient location.

A further object of the invention is to provide a safety plug in accordance with the foregoing object which may be quickly and easily applied to the upper end of a section of a drilling string or tubing and may be quickly disengaged therefrom; 1 and which when applied will effectively seal the upper end of the section and thus prevent the discharge and the contents of the section through the uncoupled lower end thereof.

A further object of the invention is to provide a safety plug in accordance with the foregoing objects which may be readily controlled and operated from a remote location, as for example by a line extending up into the derrick structure.

A still further object of the invention is to provide a safety plug in accordance with the foregoing object which shall have an improved and highly effective fastening means whereby the plug may be securely attached to the inside of the upper end of a section of drilling string or tubing and shall have a fluid tight sealed engagement therewith.

A further object of the invention is to provide a safety plug in accordance with the foregoing objects in which a considerable mechanical advantage shall be imparted to the locking elements by which the device is secured to the interior of the upper end of a section of drilling string or tubing.

These together with other objects and advantages Hce which will become subsequently apparent reside in the details of construction and operation as more fully hereinafter described and claimed,. reference being had to the accompanying drawings forming a part hereof, wherein like numerals refer to like parts throughout, and in which:

Figure l is a side elevational view of a preferred embodiment of a safety plug in accordance with this invention, the actuating lever of the device being shown in full lines in its locked or secured position and in dotted lines in its disengaged position; the position of the upper end of a section of a drilling string or tubing being indicated in phantom;

Figure 2 is a view similar to Figure 1 but taken from the left side thereof;

Figure 3 is a vertical central longitudinal sectional view taken substantially upon the plane indicated by the section line 33 of Figure 2 and showing the position of the parts when the plug is locked in the upper end of a section of a drilling string or tubing; and

Figure-4 is a horizontal sectional detail view taken substantially upon the plane indicated by section line 4-4 of Figure 3 and showing in greater detail the construction and arrangement of the slips or locking dogs of the device. i

The safety plug in accordance with this invention consists of three components or assemblies, namely a body assembly, a shaft assembly and a yoke or actuating means assembly. As shown best in .Figure l, the internally threaded upper end 10 of a box or a section of a string of drill pipe or tubing has the safety plug designated generally by the numeral 12 in accordance with this invention applied thereto, for selectively closing this upper end from the atmosphere.

The body assembly of the safety plug consists of a hollow body 16 having a generally conical exterior surface as at 18. This exterior surface is of slightly less diameter than that of the corresponding internal surface of the upper end 10 so that it will easily slide into and out of the latter. As will be readily appreciated, the safety plug will necessarily be made in different sizes in order to accommodate different sizes of upper ends 10'.

The body 16 has a generally cylindrical hollow interior or central chamber 20 which is open at its upper end and which is closed by a bottom wall 22 which ispreferably integral with the body. However, the bottom Wall is centrally apertured as at 24 for a purpose to be subsequently apparent.

At its upper end the hollow body 16 has an annular top surface 26 and there is an annular or shouldered recess 23 upon the upper and exterior surfaces of the body. A removable closure or top wall in the form of an annular plate 30 is provided for the upper end of the body and this plate likewise is provided with an annular shouldered 'recess 32 cooperating with the recess 28. Further, the top wall 30 has an axial bore 34 which is aligned with the bore 24 in the bottom wall 22. Preferably an O-ring 36 is provided in an annular channel formed in the wall of the bore 34 for a purpose which will be subsequently apparent.

A sealing means is provided between the top wall 30, the body 16 and the internal surface of the upper portion 10. This sealing means is preferably in the form of an annular ring or gasket 40 which conveniently may be L- shaped in cross-section having a horizontally extending flange 42 which lies between and is embraced by the annular flat shoulder 44 of the top wall 30 and the corresponding annular flat top end of the section or top portion 10. Further, the sealing means 40 is provided with a cylindrical depending flange 46 which is received against the convex cylindrical surface of the shouldered portion 28 of the body 16 and the annular horizontal surface lished between the top wall 30 and the upper end which 5 will seal the interior of the latter from the atmosphere.

As illustrated in Figure 3, the interior surface of the upper end10 is generally conical in configuration and is internally threaded as at 50. A locking means is provided for fixedly securing the body assembly to the upper end 10 by means of a thread 50.

For this. purpose, the body 16 is provided with a plurality radial slots 52 extending therethrough and communicating with the central chamber 20 thereof, see in particular Figures l and 2, and the plurality of locking dogs or slips 54 are slidably received in these slots. Each of the slips 54 upon its radially outward surface is provided with a series of teeth 56 which are complementary to and engaged with the corersponding threads 50 of the upper end 10. Thus, when the dogs or slips 54 are radially projected from the body through the slots 52, the teeth 56 will engage the threads 50 and thus securely lock the body assembly to the upper end 10 against relative axial movement.

A shaft assembly is provided which connects the body 16 with its top wall and with the locking dogs and which is employed as set forth hereinafter to simultaneously operate the locking dogs and the sealing means. The shaft assembly consists of a shaft 60 which is slidably received through the bore 34 in the top wall 30, passing through the O-ring 36 therein and through the bore 24 in the bottom wall 22, being provided with a headed or enlarged portion 62 at its lower end. The upper end of the shaft is threaded as at 64 and receives a lock nut 66 thereon. intermediate its ends and within the lower portion of the chamber 20 in the body 16 the shaft is provided with diametrically reduced portions 68 defining an annular channel or the like and a carrier 70 is received in this channel and is fixedly retained in position thereon as by a setscrew 72. As shown in Figure 4 the carrier is provided with a plurality of regularly extending arms 74, each of which is provided with a transversely disposed pin 76 therein. The inward portions of the dogs 54 are bifurcated and receive the outer extremities of the arm 74 and have the pin 76 loosely received in cam slots 78 therein as shown in Figure 3. It will thus be seen that the set of dogs or slips are connected to the shaft 60 through the cam slot 78, pin 76, radial arms 74 and the carrier 70. i A flat disk 80 preferably of thin sheet metal rests upon the top surfaces of the dogs and is appropriately shaped to extend into the slots 52 previously mentioned, and is further provided with a central aperture having ,an upturned rim 82. A compression spring 84 rests upon the disk 80 within the rim 82 and abuts its upper end against the underside of the top wall 30 to thereby yieldingly urge the set of dogsinto their downward position in the slots.

7 A further compression spring 86 surrounds the shaft 60, abutting at its upper end against the underside of the top wall 30 and its lower end abutting against the topside of the carrier 70 to thereby yieldingly urge the shaft 60 downwardly with respect to the body assembly.

The arrangement of the cam slot 78 is such that as the shaft is caused to move relatively downwardly, the cam radially outwardly of the body slot 72 causing the teeth of the dogs to engage with the thread 50 of the upper end 10 thus securely locking the dogs and the body assembly to the upper end against axial movement relative thereto.

The shaft assembly further includes a thrust bearing assembly as at 86 together with a cap 88 which houses the bearing assembly and is secured to the shaft 60 as by means of a setscrew 90. A similar bearing assembly 92 surrounds the upper end of the shaft 60 and abuts against the lower surface of the lock nut 66, and is retained thereagainst as by a bearing cap 94;

An actuating means for the shaft assembly consisting of a yoke assembly is connected to the two caps 88 and 94 to move the latter towards and from each other and thus to cause axial displacement of the shaft 60 with respect to the body assembly.

Referring now particularly to Figures 1 and 2. it will be observed that the yoke assembly consists of a pair of generally parallel lower links each indicated by the numeral 96. These lower links straddle and are pivoted at their lower end as by pins 98 to diametrically opposite sides of the lower cap 88. At their upper ends these links are pivoted as by pivot pins 100 to the exterior surface of the pair of furcations or arms 102 of a semi-cylindrical web member 104 which with these arms 102 comprises a yoke. The upper ends of these arms in turn are p'ivoted as by pins 106 to diametrically opposite sides of the upper cap 94. Integral with the mid-portion of the Web 104 and extending perpendicular to the arms 102 of the yoke is a lever 108 having an eye 110 in its outer end.

The arrangement of this yoke assembly is" such that when the lever 108 is disposed in its horizontal position as shown in Figure 3 and as shown in full lines in Figure l or in Figure 2, the pins 106 and 98 will be in vertical alignment and the lower links 96 will likewise be in vertical alignment with the arms of the yoke 102. Consequently, in this position, the upper and lower cap members 94 and 88 will be urged apart to their greatest distance thereby moving the shaft 60 to its uppermost position with respect to the body assembly. However, when the lever 108 is pivoted from the full line position of Figure l to the dotted line position therein, the upper pins 106 will be moved out of alignment with the lower pins 100 which joint the yoke to'the lower links will be moved to one side of the vertical line through the pins 106 and 98, thereby shortening the distance between the upper and lower caps 94 and 88 and thereby causing -a relative downward movement of the shaft 60 with respect to the body assembly.

When the shaft is moved downward, it is evident that the carrier 70 will move the pin 76 downward in the cam slot 78 thus retracting the dogs, which are retained against the lower end of the slots 52 by the spring 84, so that the plug is then released from the upper end 10 and may be readily withdrawn therefrom.

However, when the lever '108 is moved into its horizontal position, the shaft 60 is moved upwardly, the lower cap 88 will press the top plate 30 downwardly and this will simultaneously compress the-sealing means 40 against the upper end 10 and also through the carrier 70 and the pin 76 provided in the cam slot 78 will radially protect the dogs into locking engagement with'the threads 50 of the'upper end 10. Thus, the lever l08 will simultaneously' engage the sealing means and en age the locking dogs, thereby securely locking the device in position.

Conveniently, thelever 108 may be actuated from a remote distance as by securing the rope to the eye 110 thereof and up into the derrick of the drilling rig. Thus, when it is desired to unscrew the upper'section of a string of drill pipe or tubing, the plug is positioned in the upper end 10, the lever 108 is moved into a horizontal position thereby establishing the sealing engagement of the sealing means 40 and also locking the dogs 54 into engagement with the upper end 10. Thereafter thex'upper section is removed from the string of pipe or tubing. The upper section thus removed will be swung by the derrick to any suitable place away from the rest of the string of pipe or tubing and upon pulling the rope attached to the eye 110, the lever 168 will be swung into its upward or vertical position as shown in dotted lines in Figure 1. In this position the plug will be disengaged from the upper end permitting air to enter the same and thus allowing any fiuid retained in this upper section to be discharged from the lower end thereof.

It will thus be observed that there has been provided a means which may be readily applied to or removed from the upper end of a section of drilling pipe or tubing and which will seal from the atmosphere this upper end as desired. This greatly contributes to the convenience and the safety of the personnel and of the equipment when it is necessary to remove a section of a drilling string or tubing from a well bore.

The foregoing is considered as illustrative only of the principles of the invention. Further, since numerous modifications and changes Will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation shown and described, and accordingly all suitable modifications and equivalents may be resorted to, falling within the scope of the invention as claimed.

What is claimed as new is as follows:

1. A safety plug for drill pipe and tubing comprising a body adapted to be received in the upper end of a section of pipe or tubing, locking dogs mounted upon said body and slidably projectable radially therefrom into engagement with said upper end, sealing means disposed between said body and engageable with said upper end and operable to seal the interior of said upper end from the atmosphere, a shaft mounted in and movable in said body, means connecting said shaft to said dogs and other means connecting said shaft to said sealing means for engaging said dogs and sealing means with said upper end upon movement of said shaft in one direction and for releasing said dogs and sealing means upon movement of said shaft in the other direction, actuating means for said shaft, said shaft and said body having vertically spaced bearing assemblies, said shaft extending through said bearing assemblies, said actuating means comprising a toggle linkage connected to each bearing assembly,

2. The combination of claim 1 wherein said toggle linkage includes a bell crank pivoted to one hearing assembly and a pair of links pivoted to the other bearing assembly and to said bell crank.

3. The combination of claim 2 wherein said bell crank includes an eye remote from said pivotal connections for receiving a line whereby said toggle linkage may be remotely actuated.

4. The combination of claim 1 wherein said first mentioned connecting means comprises a collar surrounding and secured to said shaft, cooperating cam elements on said collar and dogs effecting radial movement of said dogs in response to axial movement of said shaft.

5. The combination of claim 1 wherein said first mentioned connecting means comprises a collar surrounding and secured to said shaft, cooperating cam elements on said collar and dogs effecting radial movement of said dogs in response to axial movement of said shaft, said cam means including cam slots in said dogs and arms on said shaft having pins slidably engaged in said cam slots.

6. The combination of claim 5 including a spring in said body engaging said dogs and yieldingly urging the latter downwardly in said body.

7. The combination of claim 6 including a second spring in said body yieldingly urging said shaft downwardly therein.

8. The combination of claim 1 wherein said sealing means includes a plate on said shaft overlying said upper end, a yieldable sealing member disposed between said plate and upper end compressible therebetween upon axial movement of said shaft in said body.

9. The combination of claim 8 wherein said plate and said body have opposed annular recesses receiving said sealing member therebetween.

References Cited in the file of this patent UNITED STATES PATENTS 405,784 Livingstone June 25, 1889 923,066 Mueller May 25, 1909 1,560,489 Yager Nov. 3, 1925 1,835,418 McHardy Dec. 8, 1931 2,670,799 Dobbs Mar. 2, 1954 

